Field of the Invention
The present disclosure relates to control of an image forming apparatus, and more particularly to control of the fixing device included in an image forming apparatus.
Description of the Related Art
Electrophotographic image forming apparatuses are commonly used. An electrophotographic image forming apparatus includes a fixing device. The fixing device includes a rotatable heating unit and a rotatable pressing unit pressed against the heating unit. The image forming apparatus heats the heating unit to fuse a toner image on a print material passing through between the heating unit and the pressing unit and fixes the toner image on the print material.
In connection with control of a fixing device, Japanese Laid-Open Patent Publication No. 2012-242635 discloses an image forming apparatus in which “the surface temperature of the heating member can be maintained in STANDBY mode within a range of setting temperatures without causing temperature overshoot or undershoot”. Japanese Laid-Open Patent Publication No. 05-289574 discloses a fixing device in which “the surface temperature of the fixing roller can be maintained to a predetermined control temperature stably and accurately without damaging the roller”.
When being powered on or when accepting a print instruction, an image forming apparatus executes a warm-up for heating the heating unit up to a printable temperature and executes a print process after completion of the warm-up lithe warm-up takes time, the waiting time for the user in printing becomes long. An image forming apparatus capable of reducing the time taken for a warm-up is thus desired.
The image forming apparatus disclosed in Japanese Laid-Open Patent Publication No. 2012-242635 is aimed to stably maintain the surface temperature of the heating member within a predetermined range. That is, the image forming apparatus is not intended to reduce the time taken for a warm-up.
The fixing device disclosed in Japanese Laid-Open Patent Publication No. 05-289574 is aimed to stably maintain the surface temperature of the fixing roller within a predetermined range. That is, the fixing device is not intended to reduce the time taken for a warm-up, either.